Study on deformation characteristics and support optimization of weak surrounding rock in fault zone

The study of deformation characteristics of weak surrounding rock around fault zone is of great significance for roadway support optimization and preventing large deformation of the surrounding rock.Based on the engineering background of Chengjiao coal mine in Henan province, surface displacement, top-plate deformation and loose ring of surrounding rock are monitored in the excavation process of the second-level west-wing track roadway.The stress of fault structure gradually decreases under the continuous influence of the excavation of roadways, and the deformation speed of the tunnel increases first and then decreases with the advance of the roadway.Therefore, the force caused tunnel deformation in fault zone mainly comes from fault tectonic stress.The deep surrounding rock is affected by fault structure, the crack is well developed, and the roof is unstable, the shallow surrounding rock has smaller abscission layer due to the excavation of the roadway.The loose ring around the fault is greatly affected by fault structure and the roof forms a large loosen ring.In this paper, the support optimization scheme of U-type steel and anchorage cable is proposed according to the results of field monitoring and actual geological conditions.